Chlorination of ethane



neezo, 193a I 2,140,547 onmnms'non or ETHANE John H. Reilly, Midland, men, ISSlllol to The Dow Chemical Company, Midland, Mich, a corporation of Michigan JNo Drawing.

Application August 28, 1936, Serial No. 98,095

This invention relates to processes for the chlorination of ethane, and, more particularly, to a process for chlorinating ethane to produce principally mono-chlorinated compounds.

5 It has been thought heretofore that, in the chlorination of ethane in either the liquid or vapor phase,; the concentration of mono-chloro compounds in the product must not be allowed to exceed 20-30 per cent, else the formation of poly-chlorinated compounds in excessive amount begins. It has therefore been considered necessary in batch processes for chlorinating ethane to separate the mono-chlorinated compounds from the reaction mixture when the concentration thereof in the mixture reaches the range above set forth; and in continuous processes to limit the amount of chlorine admixed with the ethane so that there is a major portion of un-- chlorinated ethane in the exit gases. It is, therefore, an object of the present invention to provide a process whereby sufllcient chlorine can be admixed with ethane to chlorinate the entire quantity thereof .at a single treatment, and at the same time obtain principally monochloro-hydrocarbons.

the invention to provide a process whereby ethane canbe chlorinated directly to produce ethyl chloride as the principal product of the reaction, along with substantial amounts of vinyl chloride.

I have now found that ethane can be admixed with chlorine in approximately equimolecular proportions, and the gas mixture contacted with a bath of molten metal chlorides maintained at a temperature above about 250 C.,-but below the decomposition point of ethyl chloride, to obtain aproduct containing a preponderating proportion of ethyl chloride and vinyl chloride. The composition of the molten metal chloride bath must be such as to obtain salt mixtures which are liquid at the above temperatures, preferably having a melting point at least as low as 200 C. .Mlxtures of the chlorides of aluminum, magnesium, potasslum, iron, sodium, copper, bismuth, and zinc are useful when compounded in the proper proportions to give a suitable melting point. The

eutectic obtained by mixing parts by weight of aluminum chloride, 30 parts of sodium chloride,

and 10 parts of ferric chloride is entirely suitable for my purpose. This composition hasa melting 50 point of approximately 150 C. and a boiling point above 1000 C. Copper chloride may be substituted for ferric chloride in said mixture.

The ethane and chlorine may be preheated separately. or after admixture prior to contacting u with the molten salt bath, but such preheating is It is a further object of' not necessary to obtain satisfactory results. The type of reaction vessel in which the ethane and chlorine are contacted with the molten metal chlorides is capable of considerable variation and does not form part of the subject matter of this 5 invention. The reaction product evolved from the molten salt bath is cooled to condense the chlorinated products, and any excess chlorine therein present can be re-cycled in the process. The product so Obtained can then readily be 10 separated by fractional distillation. The total yield of mono-chloro compounds obtained is generally about per cent by weight, based on the passed a mixture of ethane and chlorine in the ratio of one part by weight of ethane to three parts by weight of chlorine, at the rate of 3.6 pounds per hour. The vapors continuously evolved from thegbath were cooled to condense 30 the chlorinated product therefrom. The process was operated continuously over a period of several hours, the product collected and fractionally distilled. Of the crude product 45.9 per cent by weight was ethyl chloride, 21.9 per cent by weight 5 was vinyl chloride, and 3.7 per cent by weight was methyl chloride. Thus, the percentage of ethane converted the mono-chloro compounds amounted to 71.5 per cent. .The balance of the product was polychlorinated compounds such as 40 dichloroethane, tetrachloroethylene, trichloroethane, etc.

Another suitable mixture of molten metal chlorides which may be employed in carrying out my invention can be prepared by melting together 45 46 per cent ,by weight of aluminum chloride, 46 per cent of sodium chloride, and 8' per cent of bismuth chloride. Ordinarily the bath should be maintained between about 250 C. and about 450 C. The proportions of chlorine to ethane 50 may be varied between about 2.4 and about 3.5 parts of chlorine'per part of ethane, all by weight.

If the chlorine ratio is much greater than 3.5 parts of chlorine per part of ethane, the yield of monochlorinatedproducts is decreased. The so apparatus employed can be maintained, since the reacting gases can be put into the bath at any rate below that at which the molten bath will-be blown out of the reactor. The catalytic efliciency of the salt bath to promote the substitution reaction is substantially unchangTd over lona Deriods of time.

Other mode of applying the principle of my invention may be employed instead or those explained, change being made as regards the method herein disclosed, provided the stepor steps stated by any of the following claims or the equivalent or such stated step or steps be employed.

I therefore particularly point out and distinctly" claim as my invention:-- 7 r 1. In a process of chlorinating ethane, the step which consists in subjecting a gaseous mixture containing ethane and chlorine, in the'ratio or between about 2.4 and about 3.5 parts by weight 'of chlorine per part of ethane, to intimate contact with a liquid mass or metal chlorides maintained at a temperature above about 250 C. but below the decomposition temperature of the ethyl ch10.-

ride.

2. In a process for the conjoint production of ethyl chloride and vinyl chloride, the step which consists in passing a gaseous mixture containing ethane and chlorine, in the ratio or between about 2.4 and about 3.5 parts by weight of chlorine per part oi ethane, into a liquid mass comprising essentially a metal chloride and maintained at a temperature above about 250 C. but below the decomposition temperature of the ethyl chloride.

JOHN H. REELY. 

